The head portion of a ring wrench or socket usually has an inner shape and size complementary to that of a typically hexagonal or square fastener head. The head of such a socket or wrench has an inner surface which surrounds the fastener head with only a small amount of clearance between the inner surface of the socket or wrench and fastener head. A torque applied to the socket or wrench head is transmitted to the fastener head to turn the fastener.
Sockets or ring wrenches are preferable to open jaw type wrenches because the torque transmitted to the fastener is applied via a much larger contact area. Also a socket or ring wrench can transmit a far greater torque without harmful distortion of the fastener head and less chance of the socket or wrench head damaging or slipping off the fastener. Ring wrenches are preferable of the closed head type in order to transmit adequate torque to the fastener without the ring head opening under the applied torque causing damage or slippage. Closed ring sockets or wrenches, however, are incapable of use on pipe work fittings and fasteners where closed pipe work or other obstructions such as a vehicle tie rod prevent the fasteners being accessed. Likewise most known sockets and their various operating means cannot be used for the same reason.
Sockets that can open and close, known generically as butterfly sockets, are known. The known butterfly sockets comprise two arms connected by a swivel pin. The two arms can swivel outwards in order to access the fastener to be worked then closed around the periphery of the fastener. When the butterfly socket is closed, a spigot drive of an operating handle can be inserted through respective overlapping apertures provided in the free ends of the arms in order to lock the arms in the closed position. The known butterfly sockets incorporate a substantial swivel pin, which passes through the ends of the arms opposite the free ends. Because the free ends of the arms have to be made relatively wide to allow the provision of the apertures and the opposite ends have to be relatively wide to accommodate the swivel pin, the known butterfly sockets are relatively large, at least along a line extending though the opposite ends of the butterfly socket when closed. This can make it difficult or impossible to use such sockets when there are further pipe nuts, fasteners, fixings or other obstructions that would foul the movement of the socket.
It is an object of the invention to at least partially alleviate the above mentioned disadvantages and/or provide an alternative to existing products.